The goal of this research is to understand the role of the nervous system in controlling behavioral and physiological thermoregulation. To accomplish this aim the present work is being conducted along three lines, all involving recovery of function after brain damage. The first line is concerned with discovering the exact nature of the deficits in heat production and heat loss produced in rats by lesions in the preoptic/anterior hypothalamus. In the slow process of the recovery of the ability to regulate body temperature, we will see the separate return of each of the control mechanisms sequentially in time. There are only a few ways to maintain euthermia in the cold, such as shivering, piloerection, increased oxygen comsumption and vasoconstriction. We are measuring all these variables in normal rats and in rats with hypothalamic damage. We will make similar measures in the heat (of vasodilation, decreased oxygen consumption and salivation). The second line of attact examines the effects of intraventricular and intrahypothalamic injections of biogenic amines on both motivated and reflexive thermoregulation in normal and hypothalamically lesioned rats. We hope to ascertain when an amine alters the set point and when it merely changes the body temperature. The third line of research involves the effects of antipyretic drugs, such as salicylates, on afebrile body temperature in normal and lesioned animals. We will use behavioral techniques in all of these investigations because we define a change in body temperature as a change in set point only when there are parallel changes in reflexive and motivated behaviors.